Power steering valve system

ABSTRACT

A minimum slack connection between the steering shaft, power steering valve components, and steering gear worm, in which limited universal motion is permitted to accommodate manufacturing tolerances without interference with precise steering control; and incorporating provision against application of axial pressures to the steering components in response to power steering hydraulic pressures in the system.

United States Patent [5 6] References Cited Inventor Arthur E. Bkhop24Bl'lnker Road, st n 60010 7 UNITED STATES PATENTS pr 3 1970 3,138,0696/1964 Bishop 91/375 plied d 1" 971 3,145,626 8/1964 Vickersetal137/625.24X meme 3,296,940 1/1967 Eddy 6:61 137/625.24X

POWER STEERING VALVE SYSTEM Primary Examiner-Henry T. KlinksiekAttorneyHill, Sherman, Meroni, Gross & Simpson ABSTRACT: A minimum slackconnection between the steer- 10 Claims 5 Drawing Figs ing shaft, powersteering valve components, and steering gear U.S. CL 137/560, worm,inwhich limited universal motion is permitted to acl37/625.24,9l/375commodate manufacturing tolerances without interference lnt.Cl..Fl6kll/02, with precise steering control; and incorporating provisionF 15b 9/10 against application of axial pressures to the steering com-Field of Search l37/560,- ponents in response to power steeringhydraulic pressures in 62521-62524; 91/375 the system.

L W m \W Y [I J E :w m 1 1 1% i] 'y'i m X 3,, l9 1 5' V) /43 22 /7 /z a/4 4; ID A rowsiifl's'rssanvovatvn svs'mm BACKGROUND or The INVENTION Asthose familiar with the field of automaticsteering are aware,manufacturing tolerances required to successfully compete in themanufacture ofsteering gear in the mass production market pose seriousproblems where precise steering valve control isnecessary. In modernvehicles, a constant problem of compactness has occurred. The vehicleengine space has been consistently decreasing in order to provide a'reside in that space must be'made as compact as possible. A

reduction in steering gear size has been attempted through low vehicleprofile while at the same time the size of the en- DESCRIPTION OF THEDRAWINGS v Fig-11s a plan view, shown in cross section, of an integralpow'er'steering gear constructed in accordance with the presentinvention; v

FIG. 2 is an isometric view of a drive spring employed in the structureof FIG. 1; Y

FIG. 3 is an enlarged cross-sectional view taken along the line llllllof FIG. 1;

FIG; 4 is a modified form of drive connection taken along the sectionline IIllll of FIG. 1; and f FIG. 5 is across-sectional view taken alongthe line V-V of FIG. 4.

DETAILED DESCRIPTION I v I -As 'canbe seen from astudy of FIG. l,- aninput steering reduction of bearing size's, in highly specialized geartooth forms and in the integration of the power motor to the steeringgear housing. With the achievement of size reductions, problems'ofsealing and proper drive'connection betweenthe various parts, capable ofnonbinding operation in spite of extremely close tolerances, havearisen. It has been found to be of crucial importance that slack bereduced to a point as close as zero as possible and that relativelymovable, highly sophisticated, power steering valve parts be operablewithout binding under the same circumstances. In accordance with thepresent invention, such a valve system. is successfully pro vided. I o Iv SUMMARY ormemvsu'rioii In accordance with the'present'invention, asteering wheel a shaft is provided in driving connection with agear-reduction device through a spring-centered lost-motion connectiomApower steering valve of two relatively rotatable components is provided,one component ofwhich is'secured to the steering shaft and the other ofwhich is securedto the gear'reduction device. In a preferred form of theinvention, an hourglass worm and roller follower is employed as thereduction system.

The hourglass worm is coaxial with the steering shaft and is core whichmates with an outer valve sleeve drivingly connected to the worm.Accordingly, relative motion between the worm and the steering shaft, asabove described, causes relative motion between the valve core and valvesleeve.

In a preferred arrangement. of power steering motor and steering gearreduction mechanism, the hydraulic pressure applied to one side of thepower steering motor is applied substantially throughout the hourglassworm and roller portion of the housing. Any effect of thispressurizationmust be kept from thevalve-parts. In accordance with thepresent invention, a novel sleeve and seal combination is provided forconnecting the hourglass worm and the valve sleeve in 'a mannerisolating the end of the valve sleeve from any oil pressure forces. Atthe same time, the hourglass worm and sleeve are provided with a novelslack-free connection incorporating constant spring bias andpermittingslightaxial misalignment shaft 1 is'rotatably mounted in thesteering gear housing H in a needle bearing'Z and, at its remote end onthe torsion bar 7 by way of a sleeve bearing 3. The steeringshaft l issplined at 6 to a steering worm 5 by way of a lost motion splinepermitting, for example, approximately 9 of travel away from a centeredcondition in either direction before providing a positive drive. Thetorsion bar 7 is serrated at 4 and is forced into worm 5 providing, apermanent, rigid drive connection between. the torsionbar7andtheworm5. 11

After assembly of the torsion bar 7 into the worm 5 and shaft '1 andfollowing bench alignmentof the outer, valve sleeve 9, the torsion bar 7and shaft 1 are drilled and pinned as at 8. Fromthat point inconstruction, rotation of the steering shaft 1 will drive theworm 5through the torsion bar 7 until the torsion bar deflects as a result ofa transfer of torque to a point at which the slack in the loose splineconnection 6 is,

- tolerance, ordinarily in therange of 0.0002 inch to 0.0006

ing purposes. The steering shaft rigidly carries an inner valve o inchclearance. The alignment of the sleeve 9 within the housing H and withrespect to the worm- 5 is dependent upon a number of factors includingthe alignment of the ball bearing races 10 and I1 carrying the worm 5and the bearings 2 and 3 carrying the steering shaft 1. In manufacturingprocedures, misalignments can occur in the overall, due to-the additionof a number of factors. For example, the deflection of the bearingsunder load and the slight va'riationsin clearances in plain-bearingssuch as bearing 3 can cause substantial misalignments in the finishedproduct. Since these misalignments can occur, a clearance ofapproximately 0.012 inch'on the diameter is allowed between the sleeve 9and the housing I-I. TEFLON rings 12, 13 and 14 are carried,respectively, in annular grooves 12a, 13a and 14a to accommodate thismisalignment without oil leakage between the valve ports.

In the system shown, a power motor M is provided with a reciprocal powerpiston cooperating with the cross-shaft S by way of a rack and sectorconnection, not shown. The power 1 7 motor M is pressurized at one endvia port 30 and at the other between the hourglass worm and the valvesleeve without I binding. In accordance with thepresent invention,unbalanced pressure forces against the valve. sleeve are avoided'and, atthe 1 same. time, slight universal motion is "provided in driving thevalve sleeve from the worm, allin a compact manner.

endvia the open housing space 20 and valve groove 20a via passage 20bpast the worm 5 through the ball bearing 10. Ac-' cordingly, thepressure in the area 20 will vary from sump pressure in the system tothe maximum oil pressure employed in steering the vehicle. 0n the'otherhand, pressure in the areas 21 of the valve system will be at low sumppressure at all times. In these circumstances, it is important that thepressure acting at the right-hand end of the sleeve, as viewed in FIG.1, be substantially the sameas the pressure acting at the lefthand endof the sleeve 9'. It is necessary, accordingly, to isolate thepressureinthe passage 20b from acting against the lefthand end of the sleeve 9,thereby preventing any binding action between the sleeve 9 and the raceaccommodating the bearing 2.

'In accordance with the present invention, isolation is provided by wayof a sleeve 16. The sleeve 16 comprises an annu- 5 and is sealed withrespect to sleeve 9 by way of an O-ring or similar seal 17. As a resultof the seals 17 and 19, oil pressure from the space 20a, 20b isprevented from entering the connection between the worm 5 and the valvesleeve 9. At the same time, the O-rings 17 and 19 permit slight axialmisalignment between the wonn 5 and the sleeve 9 without disruption ofthe seal or without binding relationship. In the embodiment illustrated,it will be observed that the diameter of 'the worm 5 upon which the ballbearing is carried, and upon which the sleeve 16 is journaled, is ofsmaller diameter than the outside diameter of the sleeve 9 upon whichthe sleeve 16 is journaled. Accordingly, when the pressure in space ishigh, a resultant bias will urge the sleeve 16 toward the right asviewed in FIG. 1 unless restrained. Restraint is provided by an annularmetal-retaining ring 18 carried by the worm 5. Movement of the sleeve 16cannot occur toward the right beyond the ring 18 and, as a result,pressures resulting from the elevated pressure in space 20 can in no wayaffect an axial.

pressure against sleeve 9 toward the right, and the sleeve 9 remainspressure-balanced by the pressure of sump space 21. Vents 22 in theshaft 1 similarly assure equalization of all of the areas 21 to the sumppressure.

As a result of the sleeve construction above described, the diameter ofthe worm 5 which may be supported by the bearing 10 can be substantiallyreduced and an end-to-end or faceto-face drive relationship may beprovided between the worm 5 and the sleeve 9 while at the same timeeliminating unbalanced pressures on the sleeve 9. In prior art systems,the sleeve 9 has sometimes been axially embedded into the worm 5 toprevent the application of unbalanced pressures on the sleeve; but suchan arrangement has required substantially larger diameter bearings with,accordingly, a substantial increase in overall steering gear dimension.

The drive connection between the worm 5 and sleeve 9 is quite critical.An axial misalignment, or radial shift, of approximately 0.004 inchbetween the valve sleeve 9 and the worm 5 at their axial interfaceresults in about one-half degree angular change, or a resultingvariation in manual effort at the steering wheel rim of approximatelyone pound. A bias to right or left, of one-quarter of this amount can bediscerned by the driver and can be objectionable to him. Preferably, theslots 31 and 32 in the worm 5 and sleeve 9, respectively, are milled toa width of approximately 541 inch +0.003 inch -0.000 inch and a springcoupling member 22 is so formed that its ends lock into these slotstightly without respect to the width of the slot. Precision of theactual angular relationship between the valve sleeve 9 and the core 1is, as above mentioned, relatively unimportant since the torsion bar 7is pinned to the shaft 1 in an exact trim balanced condition within thevalve sleeve 9 at the final bench assembly. The spring 22 is shown byitself in FIG. 2 and it will be observed that the ends 22a, 22b of thespring are bent into a curved configuration shown in FIG. 3 such thatupon assembly of the device with a filler block 23 positioned betweenthe ends 22a, 22b, the slots 31, 32 are substantially completely filledin a resilient manner by the spring, independently of slight variationsin slot width. With this connection, slight universal motion may occurbetween the worm 5 and the sleeve 9 and such universal motion is takenup by resiliency of the spring 22. At the same time, no slack isprovided in the connection so that steering in all cases is firm andwithout valve flutter.

A revised embodiment of the device for providing a slackfree connectionbetween the valve worm 5 and the sleeve 9 is shown in FIGS. 4 and 5.FIG. 4 as noted above, illustrates a revision, as viewed along the samecross-sectional lines IIIIII taken in FIG. 1. Instead of providing apair of opposing, faceto-face slots and a filler block 23, however, theworm 5 is provided with a slot 31 and sleeve 9 is provided with a roundpin 33. The slot 31 may retain its original dimension and in such casethe pin comprises approximately three-sixteenth inch diameter. The spacebetween the pin 33 and the slot 31 is resiliently filled by a flatspring 34 of athickness approximate- I 0.055 inch having a sharp reversebend 34b such that the rec end of the spring 340 acts against the pin 33and the inner I end 34b cooperates with the slot 31 forcing the pin 33hard against the side of the slot at all times. This connection providesa positive, exact, relative position between the sleeve 9 and the worm 5at all times, but simultaneously permits resilient misalignment duringrotation.

In the embodiments shown in FIGS. 1 and 4, the point of connectionbetween the worm 5 and the sleeve 9 is axially outboard of the bearings10, 11 of the worm 5. Manifestly, the further the distance outboard ofthe bearings 10 and 11 this face-to-face connection is located, thegreater the misalignment error will be as a result of any misalignmentbetween the axes of the worm 5 and the shaft 1. Accordingly, it isdesired that the interface coupling between the worm 5 and the sleeve 9be positioned as close to the bearing 10 as practicable, as it has, infact, been placed in the illustrated embodiment.

It will be seen from the above description that I have provided a noveland highly effective connection between the valve sleeve and the worm ofa power steering system. This connection prevents unbalanced hydraulicpressures from being applied to the valve sleeve and provides a positiveslackfree drive connection between the worm and the valve sleeve whichaccommodates slight misalignment without binding and with substantiallyconsistent accuracy. Variations may be made in the structure withoutdeparting from the scope of the novel concepts of this invention and itis, accordingly, my intent that the scope of the invention be limitedsolely by that of the hereinafter appended claims.

I claim:

1. In combination in an integral rotary-valve power steering gear havinga gear reduction member drivingly connected to a power steering valvesleeve member and wherein varying hydraulic pressures are applied to thegear reduction member in the area adjacent said connection, theimprovement comprising a sleeve surrounding both said gear reductionmember and said valve sleeve member adjacent their point of connectionand resiliently sealed to both members by annular resilient sealingmeans permitting slight misalignment.

2. The structure set forth in claim 1 wherein said resilient seal meanscomprise annular rings of resilient material.

3. The structure set forth in claim 1 wherein restraining means areprovided preventing axial movement of said sleeve with respect to saidgear reduction member in a direction toward said valve sleeve.

4. The structure set forth in claim 1 wherein said sleeve is slidablerelative to said valve sleeve.

5. The structure set forth in claim 1 wherein said gear reduction membercomprises a worm gear.

6. The structure set forth in claim 1 wherein said connection comprisesan interface connection comprising a substantially parallel-sidedradially disposed slot in one of said members and opened axially towardthe other of said members, and means in said slot mechanically connectedwith the other member including a spring resiliently filling the spacebetween said mechanical means and said slot.

7. The structure set forth in claim 6 wherein said mechanical meanscomprises a pin carried by said other member and said spring comprises amember biasing said pin against one side of said slot by reactionagainst the other side of said slot.

8. The structure set forth in claim 6 wherein said mechanical meanscomprises a slot in the said other member and a block of solid material.

9. The subject matter of claim 3 wherein the diameter of said gearreduction member at its sealing to said sleeve is smaller than thediameter of said valve sleeve member.

10. A resilient universal connection between a pair axially facing wormand valve sleeve members of a power steering gear comprising a slot inone of said members, a pin on the other of said members extending intosaid slot, and spring means positioned between said pin and one side ofsaid slot constantly biasing said pin against the other side of saidslot.

1. In combination in an integral rotary-valve power steering gear havinga gear reduction member drivingly connected to a power steering valvesleeve member and wherein varying hydraulic pressures are applied to thegear reduction member in the area adjacent said connection, theimprovement comprising a sleeve surrounding both said gear reductionmember and said valve sleeve member adjacent their point of connectionand resiliently sealed to both members by annular resilient sealingmeans permitting slight misalignment.
 2. The structure set forth inclaim 1 wherein said resilient seal means comprise annular rings ofresilient material.
 3. The structure set forth in claim 1 whereinrestraining means are provided preventing axial movement of said sleevewith respect to said gear reduction member in a direction toward saidvalve sleeve.
 4. The structure set forth in claim 1 wherein said sleeveis slidable relAtive to said valve sleeve.
 5. The structure set forth inclaim 1 wherein said gear reduction member comprises a worm gear.
 6. Thestructure set forth in claim 1 wherein said connection comprises aninterface connection comprising a substantially parallel-sided radiallydisposed slot in one of said members and opened axially toward the otherof said members, and means in said slot mechanically connected with theother member including a spring resiliently filling the space betweensaid mechanical means and said slot.
 7. The structure set forth in claim6 wherein said mechanical means comprises a pin carried by said othermember and said spring comprises a member biasing said pin against oneside of said slot by reaction against the other side of said slot. 8.The structure set forth in claim 6 wherein said mechanical meanscomprises a slot in the said other member and a block of solid material.9. The subject matter of claim 3 wherein the diameter of said gearreduction member at its sealing to said sleeve is smaller than thediameter of said valve sleeve member.
 10. A resilient universalconnection between a pair axially facing worm and valve sleeve membersof a power steering gear comprising a slot in one of said members, a pinon the other of said members extending into said slot, and spring meanspositioned between said pin and one side of said slot constantly biasingsaid pin against the other side of said slot.